There are Forex or stock DAY traders, swing traders, relying mostly on technical analysis.  It has been shown that a small minority of them achieve a net gain over time.  Like poker, the only real skill required is to think slightly ahead of most others. 

WIth BTC, most traders and investors have no idea what has caused exponential appreciation.  They give up on trying to figure that out, and all that remains is technical analysis.  Technical analysis is ultimately just formulaically assessing social psychology.  As time goes on, bubbles, pumps, dumps, and other 'FOMO' behavior has become smaller and smaller.

I suspect that in recent years some whales have agreed to make random or pseudo-random market shifts.  Until then, fundamental analysis, and the understanding that BTC absolutely has an intrinsic value, despite it being a currency, predicted most of the shifts.

I couldn't help but notice how many posters wrote "Yes, you should know technical analysis" instead of "I have made a LOT of money using technical analysis".  There's no question that the guru's that teach it make tons of money via add support or selling memberships and courses.